β-Amyloid (D54D2) XP® Rabbit mAb recognizes endogenous levels of total β-amyloid peptide (Aβ). The antibody detects several isoforms of Aβ, such as Aβ-37, Aβ-38, Aβ-39, Aβ-40, and Aβ-42. APP/β-Amyloid (NAB228) Mouse mAb detects endogenous levels of APP/β-Amyloid protein. Although this antibody recognizes both the phospho and non-phospho forms of the protein, it has been shown to prefer the phosphorylated form in some systems. BACE (D10E5) Rabbit mAb detects endogenous levels of total BACE protein. Phospho-GSK-3α (Ser21) (36E9) Rabbit mAb detects endogenous levels of GSK-3α protein when phosphorylated at Ser21, and does not detect GSK-3β when phosphorylated at Ser9. GSK-3α/β (D75D3) XP® Rabbit mAb detects endogenous levels of total GSK-3α and GSK-3β protein. The antigen is 100% conserved between GSK-3α and GSK-3β in humans, monkeys, mice, and rats. Neurofilament-L (C28E10) Rabbit mAb detects endogenous levels of total Neurofilament-L protein. α-Synuclein (Syn204) Mouse mAb detects endogenous levels of total synuclein protein. This antibody detects recombinant α but not β-synuclein (Giasson, B.I. et al., 2000). Tau (Tau46) Mouse mAb detects endogenous levels of total tau protein, and also cross-reacts with MAP2 at 280 kDa. This antibody is predicted to detect all six isoforms of tau based on the amino acid sequence.

Alzheimer's Disease (AD) is one of the most common neurodegenerative diseases worldwide. Clinically, it is characterized by the presence of extracellular amyloid plaques and intracellular neurofibrillary tangles, which results in neuronal dysfunction and cell death. Central to this disease is the differential processing of the integral transmembrane glycoprotein Amyloid β (A4) precursor protein (APP) that exists as several isoforms (1). The amino acid sequence of APP contains the amyloid domain, which can be released by a two-step proteolytic cleavage (1). β-secretase (BACE) is an aspartic acid proteinase that catalyses the initial step in APP processing by cleaving and releasing a soluble, extracellular APP-β (sAPPβ) ectodomain and generating a membrane-bound, carboxy-terminal fragment consisting of 99 amino acids (CTF99). Additional processing of CTF99 by γ-secretase generates the amyloid β-peptide (Aβ) that forms aggregates in the brains of AD patients. BACE is an attractive target for inhibitors in AD therapy since it catalyses the first and rate limiting step in amyloidogenic APP processing (2). Pro-BACE-1 is synthesized in the ER before it is transported to the trans-Golgi network to undergo maturation (3). The extracellular deposition and accumulation of the released Aβ fragments and an α-synuclein fragment known as the non- Aβ fragment, form the main components of amyloid plaques in AD. GSK-3α regulates the production of Aβ peptides. Administration of therapeutic concentrations of lithium, a GSK-3 inhibitor, attenuates Aβ production by specifically inhibiting the cleavage of APP by γ-secretase, thereby blocking accumulation of Aβ peptides in the brains of mice that overproduce APP (4). AD is also characterized by the presence of neurofibrillary tangles. These tangles are the result of hyperphosphorylation and oligomerization of the microtubule associated protein Tau and lead to apoptosis of the neuron. In particular, phosphorylation of Tau Ser396 by GSK-3 or CDK5 destabilizes microtubules in AD (5,6). Additionally, neurofilaments are the major intermediate filaments found in neurons and consist of light (NFL), medium (NFM) and heavy (NFH) subunits (7). Accumulation of neurofilaments are found in many human neurological disorders including AD (7).